The present invention relates to a resettable overcurrent protective circuit which cuts off an overcurrent to protect a load circuit when an overcurrent flows therethrough.
A breaker cannot interrupt an overcurrent very quickly due to its mechanical operation. Therefore, there has been a problem that a breaker cannot be used in a circuit which requires a rapid cut-off operation such as an IC semiconductor circuit. Also, there has been another problem that a breaker requires a mechanical operation to be reset.
In Japanese Patent Unexamined Publication Nos. 3-48456 and 5-167021, and PCT Publication No. WO 94/18736, an overcurrent protective circuit is disclosed which is connected in series between a power source and a load circuit, and in which the sources of an N-type depletion mode FET and a P-type depletion mode FET are connected to each other, the drain of the N-type depletion mode FET is a positive terminal, and the drain of the P-type depletion mode FET is a negative terminal. The disclosed overcurrent protective circuits operate to cut off an overcurrent to protect a load circuit when the overcurrent flows therethrough. In the case that, subsequently, the overcurrent returns to a normal level, it is, however, necessary to use a troublesome operation of disconnecting the overcurrent protective circuits from the power source in order to restore them from the cut-off state to the normal current-carrying state.